The proposed work will focus on studying the ultraviolet circular dichroism spectra of poly d(G):d(C) preparations made by four different enzymatic techniques, in order to accurately characterize the spectral properties of the pure one-to-one double-helical complex of polydeoxyguanylate and polydeoxycytidylate. This information will the be used to upgrade a previously defined analytical procedure for obtaining the nearest-neighbor frequencies of natural DNAs from their CD spectra. The procedure will be applied to the analysis of the CD spectra that have already been obtained for several satellite DNAs which have sample repetitive sequences.